Bleeding the Cooling System

Okay... so I've had LT1 cooling systems apart a billion times...

This time, when I buttoned up the '94, I bled the system per usual - while adding coolant I had the valve cracked, then I started the car w/o a cap, let it warm up, bled it again, put on the cap, drove it, bled it again. This is usually all it takes.

Parked it yesterday, and it puked up a bunch of coolant. I pulled the expansion tank cap, and it was very low. Added some coolant, and grabbed the cap from another car because the cap had a little spring that was out of place - I think it was bad and the system couldn't achieve pressure.

So... now all seems fine, but I'm getting the waterfall sound at the heater core. I've bled the system a bunch of times, and I just can't seem to get the noise to stop.

Any suggestions? Is my heater core perhaps clogged? It (the heater core) is only a couple years old, but I guess anything is possible!

Thanks in advance!

You may of tried this but I usually jack the front of the car up as far as I can and then go through the bleeding process. Doing it this way I can normally do it in one shot.

Bill